Refueling stations for vehicles may have fuel dispenser pumps that dispense gasoline (or other fuel blend) or diesel fuel, to accommodate vehicles that run off of either fuel type. However, if diesel fuel is unknowingly introduced into a gasoline engine, engine parts may be damaged. For example, diesel fuel is heavier and more oily than gasoline. Thus, introduction of diesel fuel into a gasoline engine may result in clogging of fuel injectors, and may further result in spontaneous ignition of the diesel fuel inside gasoline engine cylinders. Such adverse actions may result in high repair costs, associated with rebuilding the vehicle engine, in some examples, in addition to draining out the diesel fuel and flushing the fuel system including the fuel pump, fuel filter, and fuel injectors. In still other examples, if high reid vapor pressure fuel (e.g. 13 psi) is being dispensed from gas stations in a particular vicinity, for example during winter months, and low reid vapor pressure fuel (e.g. E85 or E100) is introduced to a non-flexible fuel vehicle, engine starting problems may result.
To discourage the introduction of diesel fuel into gasoline engines (or vice versa), many gas stations include refueling nozzles that differ for gasoline compared to diesel fuel. For example, gasoline dispenser nozzles may differ from diesel nozzles in diameter. Thus, the nozzles may be designed such that a diesel nozzle does not readily fit into a fuel filler neck configured for a gasoline engine. In still other examples, dispenser nozzles may additionally or alternatively be color coded, to illustrate to a dispenser operator which nozzles are gasoline, or other fuel blend, as compared to diesel fuel. However, in some world markets, a similar nozzle diameter and color may be used for both diesel fuel and gasoline, for example, thus making it challenging to prevent misfueling of vehicles.
Diesel fuel differs from gasoline in that diesel fuel does not vaporize readily, as compared to gasoline. For example, the hydrocarbons in diesel fuel mainly comprise heavy ends (C8-C12), unlike gasoline, which has light ends such as propane and butane that evaporate readily. Similarly, fuel blends such as E85 or E100 differs from gasoline in that E85/E100 does not vaporize readily, unlike gasoline. The inventors herein have thus recognized that differences in fuel volatility may be used as an indication of misfueling.
US Patent Application US 20160061802 A1 teaches a method for determining volatility of fuel in a fuel storage system, including determining that a refueling event has occurred and that the fuel storage system has been subsequently sealed, performing a first pressure measurement at a first time, and a second pressure measurement at a second time (the second time occurring after the first time), determining a pressure evolution rate from the first pressure measurement and the second pressure measurement, and deriving an estimation of the volatility of the fuel from the pressure evolution rate. However, the inventors herein have recognized potential issues with such an approach. Specifically, the method may only be utilized to infer fuel volatility after the fuel storage system has been filled with fuel and subsequently sealed. Thus, the method does not prevent fuel from being added to the fuel storage system, as the method may only detect fuel volatility after the refueling event has completed. Furthermore, US 20160061802 A1 teaches that knowledge of fuel volatility may be useful for controlling fuel injection amount, injection timing, ignition timing, and for conducting diagnostic procedures related to indication of the presence or absence of undesired evaporative emissions, but does not mention the use of the method to infer misfueling of the fuel storage system.
The inventors herein have recognized these issues, and have developed systems and methods to at least partially address the above issues. In one example, a method is provided, comprising during refueling a fuel tank of a vehicle via a refueling dispenser, routing fuel vapors from the fuel tank to a fuel vapor storage canister positioned in an evaporative emissions system that is coupled to the fuel tank; and responsive to an indication of misfueling comprising addition of an incorrect fuel type to the tank, sealing the fuel tank to actively induce a shutoff of the refueling dispenser.
As an example, during refueling, actual pressure in the fuel tank may be monitored via a fuel tank pressure sensor, and an expected pressure may be determined. At least one misfueling pressure threshold may be adjusted based at least in part on the expected pressure in the fuel tank during refueling, and misfueling may be indicated based on whether the actual pressure is above, or below, the adjusted misfueling pressure threshold(s). One example includes monitoring a fuel fill level in the fuel tank during refueling the tank via a fuel level sensor positioned in the fuel tank, and indicating a dispense rate of fuel into the fuel tank based on a fuel fill level change over a predetermined time period. The dispense rate may be determined via multiplying a capacity of the fuel tank by the fuel fill level change over the predetermined time period, and the expected pressure in the fuel tank during refueling may be a function of the dispense rate of fuel into the fuel tank. By monitoring an actual pressure in the fuel tank, an indication of misfueling may be determined by comparing the actual pressure to the misfueling pressure threshold(s). By sealing the fuel tank to actively induce a shutoff of the refueling dispenser responsive to the indication of misfueling, further addition of the incorrect fuel type to the fuel tank may be prevented. Furthermore, the vehicle operator may be alerted to the fact that misfueling has occurred, such that the engine is not activated subsequent to the indication of misfueling, and prior to taking mitigating actions to remedy the misfueling. By preventing engine operation subsequent to an indication of misfueling, complications arising from operating the engine with an incorrect fuel type may be avoided.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.